'I presume they've agreed to spare your life,' I said bitterly.

'And yours, Aleksei. They have no quarrel with us. They understand you killing them. If we'd told you the truth from the start, you wouldn't have over-reacted.'

He was utterly deceived; deceived by himself as much as by the Oprichniki into the conviction that because their cause – our cause – was right then they themselves must be righteous; deceived into the belief that because they were righteous, anything that they did to support our cause must be to the good. And yet through it all, the thought popped into my head that there was something I had been meaning to tell him next time I saw him. It wasn't relevant, unless Dmitry was in an even greater state of self-delusion than I could possibly believe, but there was little else to discuss.

'Did you hear that Yelena Vadimovna has had a little boy?' As I spoke, my thoughts went to Marfa and an idea began to form.

'That's nice,' said Dmitry. 'Vadim will be pleased.' I was shocked that he did not know, but also relieved that his present attitude was based upon ignorance.

'You have no idea, do you?' I said to him, as I slipped my hand inside my shirt.

'What do you mean?'

'Vadim Fyodorovich is just over there,' I said, gesturing towards where the rotting corpse hung, as yet unnoticed by Dmitry. 'They…'

Iuda had been listening and interrupted me. 'We have decided what we are going to do,' he announced loudly.

We never heard his plans. As he spoke I withdrew my hand from my shirt with a jerk. I felt the chain snap around my neck, leaving me free to pull out the icon that Marfa had given me. I held it up to the soldier's face and ominously shouted at him, 'Keep back!'

In the face of the Saviour's image, the voordalak's entire strength began to wither away. He released his grip on me and covered his eyes, backing away from me across the room.

The reaction of the other vampires was quite different.

'You fool!' shouted Pyetr at the terrified creature.

'Don't be so damned superstitious!' added Iuda. Pyetr gave a brief hand signal to Andrei, who marched across the room and, without fear, grabbed the icon from me and cast it into a corner. Evidently, there was nothing real for them to fear in the religious symbol, but the young, inexperienced vampire believed that there was, and that was enough to make him afraid. Fortunately, the moment's distraction gave me time to place my hand on something which could have a very real effect on them.

As Andrei turned back towards me I grasped my sword and, with a single backhand motion, drew it and struck him across the front of the throat. Ever since Iuda had mentioned it, I had been itching to try decapitation as a method for despatching one of these creatures. It was not, as I knew from battle, an easy thing to achieve. The blade slipped over the top of his Adam's apple and, severing his windpipe, buried itself about halfway through his neck. With a swift tug I extricated it. The wound was not fatal. Andrei bent forward, his hands clutching at the long, deep gash in his throat as a torrent of blood flowed out between his fingers. He was incapacitated, and his death was not my immediate concern. I dashed towards the window once again, this time stepping first on to the seat and then the back of the armchair that stood near to it and leaping as high as I could. I thrust the tip of my sword hard down into the wooden planks to give me a little more upward momentum. My left hand just grasped the top of one of the floorboards that covered the glass and with my two fingers I hung there above the room for five or even ten seconds, viewing the scene beneath me.

On one side of the room, Dmitry, Iuda and Pyetr stood stock still, not in shock, but unable to make any move until they could see what would happen next. On the other, Andrei stood quite upright with his back to the wall. His left hand pressed against the wall behind him for support, while his right was held ineffectually across his throat, having little effect on the flow of blood from it. Near him crouched the soldier, covering his head in fear – fear either still of the icon, or of the horrific injury I had inflicted upon Andrei.

My entire weight was held on my two fingers, and they began to scream at me that they could not hold on. Beneath me, Iuda and Pyetr were almost licking their lips in anticipation of my fall. I felt my body gradually begin to descend. But it was not my fingers that had given way, it was the board itself. With the screeching sound of nails being drawn out of wood, the floorboard I was holding yielded. As its tip etched out a quarter circle across the room, moving horizontally at first and then smoothly bending round to its final, rapid, vertical descent, I fell with it.

I landed on my feet, but immediately fell on to my side, managing to keep hold of my sword. Where the wooden plank had been, now sunlight could penetrate as a beam which sliced across the room, bisecting it with an area of light about the thickness of a brick wall. For the vampires, it was just as impassable. I had landed on the wrong side of the division, being at the feet of Iuda and Pyetr, but for me the barrier was as impenetrable as mere air. I rolled across to the other side of the room and got to my feet.

Iuda was enraged. He leapt towards me with a look of unutterable malevolence on his face, and it took the combined strength of both Pyetr and Dmitry to keep him from crossing through the intrusion of light that would so certainly have meant his death.

I smashed the hilt of my sword into Andrei's stomach and he doubled up in pain, his hands leaving his throat to clutch at his belly. The back of his neck was now fully exposed to me and I brought the blade of my sabre down on it with the strength of both hands. Still it was not enough to sever it. I could feel my sword trapped tightly between two vertebrae, unable to move forward or backward. I flicked my wrist and gave the blade a sharp sideways twist. I heard the popping sound of whatever ligaments remained to hold Andrei's head upon his shoulders and felt the blade come free.

Andrei's head was dust before it ever hit the ground. His body straightened up and his hands went to where his face had once been. They too never made it, desiccating and then crumbling to nothing as his body fell to its knees. It was a falling motion that was never stopped. By the time he had reached his knees, his whole body was no more than a fine powder which settled, rather than fell, to the floor. At some moment during the descent his coat, his shirt and his breeches ceased to be carried down by his body and began to fall of their own accord as a heap of laundry – as a marionette whose strings had been suddenly cut.

The looks of horror on the faces of Pyetr and Iuda were nothing compared with that of Dmitry. Theirs were angry and vengeful. His was a genuine shock to see his friend Andrei slaughtered before his eyes and to see his friend Aleksei carrying out the butchery with such evident satisfaction.

'Take him, Dmitry Fetyukovich!' growled Pyetr. 'You're the only one who can.'

Dmitry approached the wall of light, but even he seemed reluctant to cross it. There were tears in his eyes as he spoke.

'Why, Aleksei?' he said. 'You of all people are an enlightened man. You don't have to wallow in the prejudices and superstitions of our grandparents. They came here to help us, to fight against our enemies as though they were our brothers. Throughout their lives they've had to face the hatred of the ignorant and now you – even after they helped us to throw out the French – even you can offer them no thanks but death.'

He drew his sword and took a step towards me, standing in the middle of the very barrier that split the room, his face and his scars and his tears illuminated by the sunlight.